Stabilized fuel composition comprising a hydrazine and certain amines



3,283,5h7 Patented Nov. 8, 1966 3,283,507 STABILIZED FUEL COMPOSITION COMPRISHNG A HYDRAZINE AND CERTAlN AMINE John Farrar, Sepulveda, and Robert W. Sprague, Santa Ana, Calif., assignors to North American Aviation, line. No Drawing. Filed Jan. 31, 1962, Ser. No. 170,857 3 Claims. (Cl. 60215) This invention relates to stabilized hydrazine compositions. More particularly, this invention relates to novel hydrazine composition-s containing additives which inhibit thermal decomposition.

Hydrazine, N H,, is a well-known rocket fuel. However, unusual and severe difliculties are frequently encountered in the use of hydrazine. Most liquid fuel rocket engines today utilize propellant as a cooling means for the combustion chamber. This is called regenerative cooling and the fuel transverses the length of the engine chamber in cooling passages provided prior to its being fed into the engine to be ignited. Under certain operating conditions there exists an explosive decomposition of hydrazine. When these conditions occur, the explosions originate in the cooling pass-ages surrounding the engine chamber. It is believed that bubbles of vapor form on the hot metal surface reducing the rate of heat transfer, with a resultant consequence of local overheating. This in turn causes heterogeneous decomposition of hydrazine to commence with evolution of heat, formation of gaseous decomposition products and further rise in local temperature. Eventually, conditions are reached at which tubes rupture and explosions occur. The heterogeneous or surface effects have a contributory influence in this case because (1) not all hardware components are fabricated of catalytically inactive materials such as nickel which can be replaced or completely passivated, and (2) complete descaling, cleaning and passivation of all interior surfaces is difiicult and impossible to insure through inspection. Therefore, a need exists for a stabilized hydrazine fuel which can be used with a storable oxidizer to provide a rocket propellant fuel system having a high specific impulse.

It is an object of this invention to provide an improved hydrazine-containing rocket fuel composition. Another object of the invention is to stabilize hydrazine when in contact wit-h hot metal surfaces. It is also an object of this invention to provide a method of operating a liquid fuel rocket engine. The above and other objects of this invention will become more apparent from the discussion which follows.

The objects of this invention are accomplished by providing a hydrazine-containing fuel having certain additives therein for the purpose of stabilizing the fuel from thermal decomposition upon contact with reactive hot metal surfaces such as nickel, stainless steel and aluminum. It has been found that the addition of these certain agents to a hydrazine-containing fuel greatly reduces the thermal decomposition of the hydrazine. Particularly good results have been obtained from using the particular agents which will hereinafter be enumerated in detail at concentrations from about 0.1 to about percent by weight of the hydrazine composition. Even further superior results have been obtained when adding from about 0.4 to about 10 Weight percent of the additive. As will be seen, the rate of decomposition of hydrazine has been reduced by over 95 percent through the addition of some of the agents disclosed.

The hydrazine type fuel compound employed the composition of this invention has the general formula:

wherein R R R and R are hydrogens or hydrocarbon groups. When hydrocarbon groups are substituted for the 'hydrogens on hydrazine, the specific impulse of the compound is decreased, speaking in teams of rocket fuel performance. Hence, a preferred embodiment of this invention comprises a composition in which at least about percent of the total number of the R R R and R groups are hydrogen atoms. Another preferred embodiment comprises a composition in which at least about percent of the total of R R R and R groups in said compositions as a whole are hydrogen atoms, in which case a minimum decrease of specific impulse is occasioned. Another embodiment is a composition in which the hydrazine compound has at least one hydrogen atom attached to each nitrogen as when R and R are hydrogen atoms.

are enhanced.

An especially preferred embodiment of this invention comprises a composition where the R R R and R groups are substantially all hydrogen atoms, in which case the particular hydrazine-containing composition has the maximum specific impulse in proportion to its hydrazine content.

The hydrocarbon groups which replace the hydrogen atoms, on the hydrazine, have from about 1 to about 12 carbon atoms. Since, however, the specific impulse decreases the nurn'ber of carbon atoms in the hydrocarbon group, it is preferable that the latter have trom one to about eight carbon atoms. The hydrocarbon groups can be alkyl, cycloalkyl, aryl, arylkyl, alkaryl, and the like. Non-limiting examples of hydrazine compounds are: hydrazine, methylhydrazine, unsymmetrical dimethylhydrazine, trimethyl'hydrazine, tetramethylhydrazine, ethylhydrazine, N,N-diethylhyd-razine, N,N-methylethylhydrazine, propylhydrazine, N,N-dibutylhydrazine, phenylhydrazine, N,N-diphenylhydrazine, N,N-methylphenylhydrazine, dodecylhydrazine, and the like. Particularly preferred are hydrazine, unsymmetrical dimethyl hydrazine and m-onomethyl hydrazine.

One group of compounds that have been found to stabilize hydrazine against thermal decomposition are aromatic amines have the general formula:

In Formula I, R is selected from the class consisting of hydrogen and methylene and R is selected from the class consisting of hydrogen, methylene and a methylidene group. When R is a hydrogen, R is a hydrogen; and when R is a methylene group, R is a methylene or (a methylidene) group. When R is a methylene group, the dotted line represents a bond between R and R X is selected from the class consisting of phenyl, nitrogen, halo-gen and alkyl groups having from 1 to 6 carbon atoms and y is an integer from 0 to 1 such that when R is hydrogen or a methylidene group, y is 0 and when R is a substitute methylene group, y is l.

Non-limiting examples include: dipyridyl, o-phenanthroline; S-chloro-l,IO-phenanthroline; 5-nitro-l,lO-phenanthroline; 5 methyl-1,10 phenanthroline; 5 phenyll,10-phenanthroline. Hydrazine compositions containing 15 Weight percent dipyridyl and 1 weight percent o-phenanthroline are examples of fuels prepared in accordance with this invention.

Another group of compounds that have been found to be successful in reducing the decomposition of a hydrazine fuel are aiminocarboxylic acids having the general formula:

In the latter instance, performance in physical properties of the hydrazine compound as a rocket fuel wherein x is 0 or 1, and R is selected from the class consisting of hydrogen and a univalent organic radical. R is selected from the class consisting of hydrogen, an aralkyl group of 7 carbon atoms and an alkyl carboxylic acid radical having 2 to 3 carbon atoms. R is selected from the class consisting of hydrogen and a univalent organic radical. It is preferred that when R is an organic radical it has from 1 to 9 carbon atoms and is selected from the class consisting of unsubstituted and substituted alkyl, aryl, aralkyl, cycloalkyl, and nitrogen-containing heterocyclic groups wherein the substituted groups have substituents selected from the class consisting of oxygen, ni-

trogen and halogen radicals.

It is preferred that when R is an organic radical it has from 1 to 9 carbon atoms and is selected from the class consisting of hydrogen, substituted and unsubstituted alkyl, aryl, aralkyl, cycloalkyl groups wherein the substituted groups have substituents selected from the class consisting of oxygen, sulfur nitrogen and phosphorous. When phosphorous is a substituent, it is usually present in the form of a phosphonic acid radical. When sulfur is a substituent, it is usually present in the form of sulfo radicals. When nitrogen is a substituent, it is usually present in the form of an amino, imidazole, indyl, or pyrrolidine radical. When oxygen is a substituent, it is usually present in the form of a hydroxy, carboxy, or keto radical.

Non-limiting examples of compounds within the scope of Formula II include: N,N-di(B-dihydroxyethyl)glycine, fl-alanine, glycylaline, glycine glycylglycine, glycylglycylglycine, ethylenediamine-N,N-diacetic acid, glycine. Hydrazine fuel composition containing additives within the scope of Formula II include: N,N-di(B-dihydroxyethyl) glycine dissolved in the amount 5 weight percent in by drazine, and 0.1 weight percent of fi-alanine in N,N'-diphenyl hydrazine.

A preferred group of amino carboxylic acid compounds are those of Formula II in which x is O and R and R are hydrogen. These compounds have the formula:

(III) H R 0 I II wherein R is as defined in Formula II above.

Non-limiting examples include: asparagine, aspartic acid, glycine, glutamic acid, histidine, leucine, methionine, phenylalanine, serine, tryptophan, tyrosine, di-iodotyrosine, and valine and the like.

Hydrazine fuel compositions containing the compounds of Formula III include: hydrazine containing 8 weight percent of asparagine, 0.1 weight percent of glycine in hydrazine, and 5 weight percent of glutonic acid in hydrazine.

Another preferred group of amino carboxylic acids are compounds of Formula II in which R is an alkyl carboxylic acid radical of 2 to 3 carbon atoms in length having the general formula:

(IV) (OHQXCOOH wherein R is as defined for Formula II above and x is 1 or 2.

Non-limiting examples include: fl-alanine-N,N-diacetic acid; aminobarbituric acid-N,N-diacetic acid; 2-aminobenzoic acid-N,N-diacetic acid; 3-aminobenzoic acid- N,N-diacetic acid; 4-aminobenzoic acid-N,N-diacetic acid; [B-aminoethylphosphonic acid N,N-diacetic acid; B-aminoethyl-sulfonic acid-N,N-diacetic acid; aminoethylphosphonic acid N,N-diacetic acid; ammoniadiacetic acid; ammoniadipropionic acid; ammoniatriacetic acid; anilinediwherein R and R are organic radicals.

4 acetic acid; 2-sulfo-anilinediacetic acid; 3-sulfo-anilinediacetic acid; 4-sulfo-anilinediacetic acid; 1,2-diaminocyclohexane-N,N-tetraacetic acid; 1,3-diaminocyclohexane- N,N-tetraacetic acid; 1,4-diaminocyclohexane-N,N'-tetraacetic acid; ethylenediamine tetraacetic acid (EDTA); N- benzylethylene-diamine triacetic acid; N-butylethylenediamine triacetic acid; N-cyclohexylethylenediamine triacetic acid; ethylenediaminedipropionic acid; ethylenediaminetetrapropionic acid; glycine-N-propionic acid; methylamine-N,N-diacetic acid; trimethylenediamine tetraacetic acid; tetramethylenediamine tetraacetic acid; pentamethylenediamine tetraacetic acid; N-hydroxyethylethylenediamine triacetic acid.

Compositions of the above group which are prepared in accordance with the invention include 0.1 weight percent acid in hydrazine, 6 weight percent of EDTA in unsymmetrical dimethyl hydrazine, and 10 weight percent of N-hydroxyethylethylene-diamine triacetic acid in dodecyl hydrazine.

Another group of compounds that have been found to be successful are hydroxy acids having the general formula:

( R -COOH wherein R is a hydroxy-substituted hydrocarbon having 1 to 6 carbon atoms and is selected from the class of alkyl and phenyl radicals and wherein the number of hydroxy groups attached to the hydrocarbon is an integer from 1 to 3.

Non-limiting examples include: citric acid, glutonic acid, glyceric acid, glycolic acid, B-hydroxybutyric acid,

lactic acid, malic acid, salicylic acid, tartaric acid and the like.

From the above-enumerated compounds, preferred hydrazine compositions include 6 weight percent of glutonic acid in hydrazine, 0.4 weight percent of tartaric acid in unsymmetrical dimethyl hydrazine and 12 weight percent of glycolic acid in hydrazine.

Still another group of compounds that have ben found to be successful are phosphates having the general formula:

(VI (H H0 1| o] H wherein x is an integer from 2 to 3.

Hydrazine compositions that contain the above additives include 1 weight percent of pyrophosphoric acid in hydrazine, and .5 weight percent tripolyphosphoric acid in hydrazine.

A further group of phosphates which are utilizable have the general formula:

wherein x is an integer from 1 to 2. Compositions utilizing compounds of Formula VII include: 0.5 weight percent trimetaphosphoric acid in monomethyl hydrazine and 14 weight percent tetrametaphosphoric in unsymmetrical dimethyl hydrazine.

Additionally, good agents are fi-diketones having the general formula:

It is preferred that R and R have from 1 to 10 carbon atoms and are individually selected from the class consisting of substituted and unsubstituted alkyl, aryl and heterocyclic groups wherein the substituted groups have substituents selected from the class consisting of oxygen, fluorine, sulfur and silicon radicals. When either R and R are u! heterocyclics they may be selected from the class consisting of thenoyl and furoyl groups. When fluorine is present as a substituent, it may be in the form of a trifluoromethyl radical. When silicon is present as a substituent, it may be in the form of a silane.

Non-limiting examples include: acetylacetone, benzoylacetone, benzoyltrifiuoracetone, dibenzoylmethane, 1,3- disilane-1,3-propanedione, dithenoylmethane, furoylacetone, Z-furoyl-benzoylmethane, Z-furoyltrifluoroacetone, hexafluoracetylacetone, pentane-2,4-dione, C-methylacetylacetone, ,B-napthoyltrifluoroacetone, 1-methyl-3-silane- 1,3-propanedione, Z-thenoyl-benzoylmethane, 2-thenoyl-2- furoylmethane, thenoyltrifluoracetone, trifiuoroacetylacetone.

Of the above-enumerated compounds, hydrazine fuel compositions include 1.8 weight percent of acetylacetone in hydrazine, 15 weight percent of benzoylacetone in monomethyl hydrazine, and 0.5 weight percent trifiuoroacetylacetone in hydrazine.

Another group of compounds that have been found to be be successful as stabilizing agents for hydrazine fuels are oxines having the general formula:

wherein x may vary from 1 to 4 and R is selected from the class consisting of alkyl radicals of 1 to 3 carbon atoms, hydrogen, halogen, amino, nitro and sulfonic acid groups. R is selected from class consisting of hydrogen and methyl radicals.

Non-limiting examples include: oxine; Z-methyloxine; Z-methyl-oxine; oxine-N-methochloride; S-methyl-oxine; S-n-propyl-oxine; S-chloro-oxine; 7-chloro-oxine; 5,7-dichloro-oxine; S-nitro-oxine; 7-iodo-5-chloro-oxine; oxine- -sulfonic acid; oxine-S-carboxylic acid; 4-amino-oxine; S-amino-oxine; 7-amino-oxine; and 5,7-diamino-oxine.

Of the oxines set forth above, compositions prepared in accordance with this invention include 10 weight percent of oxine in hydrazine, 0.4 weight percent 7-chloro-oxine in hydrazine, and weight percent 4-aminooxine in monomethyl hydrazine.

Another group of compounds that have been found to be successful are derivatives of salicylaldehyde having the general formula:

(R10): wherein x varies from 1 to 2 and R is selected from the class consisting of halogen atoms, alkyl groups of from 1 to 3 carbon atoms, hydroxyalkyl groups of from 1 to 2 carbon atoms, nitro and sulfo radicals.

Nonlimiting examples include: salicylaldehyde, 3- chloro-salicylaldehyde, S-chloro-salicylaldehyde, 4,6-dimethylsalicylaldehyde, 3-ethoxy-salicylaldehyde, 3-fiuorosalicylaldehyde, 4-methoxy-salicylaldehyde, S-methyl-salicylaldehyde, 3-nitro-salicylaldehyde, 4-nitro-salicylaldehyde, S-nitro-salicylaldehyde, 3-N-propyl salicylaldehyde, S-sulfo-salicylaldehyde.

Compositions of the above compounds prepared in accordance with the invention include 9 weight percent of salicylaldehyde in trimethyl hydrazine and 0.1 weight percent of 3-nitro-salicylaldehyde in hydrazine.

Still another group of compounds that have been found to be successful are compounds having the following general formula:

( SHE H2N C 12)xNHR11 wherein x is 0 or 1, R is selected from the class connitroso-Z-napthol,

6 sisting of hydrogren and the cyano radical, R is selected from the class consisting of wherein R is selected from the class consisting of a phenyl group and condensed aromatic ring structures of 2 to 3 rings wherein the nitroso and hydroxy groups are attached to adjacent carbon atoms.

Non-limiting examples include: l-nitroso-Z-phenol, 1- 1-nitroso-2-anthrol, and 1-nitroso-2- phenanthrol.

Compositions prepared utilizing the above compounds include 9 weight percent of l-nitroso-Z-napthol in hydrazine.

Polyamines having the general formula are included herein:

(XIII) /Ri7 wherein x is an integer from 1 to 3, R is selected from the class consisting of hydrogen and methyl radicals, and R is an alkylene group of from 1 to 3 carbons in length. R and R are individually selected from the class consisting of hydrogen, methyl and ethyl radicals.

Non-limiting examples include: N,N'-dimethylethylenediamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, triethylenetetramine, tetraethylene pentamine, trimethylenediamine, methylethylenediamine.

Compositions prepared utilizing the amines a'bove-described prepared in accord with the invention include 0.4 weight percent of tetraethylene-pentamine in a mixture of 10 weight percent monomethyl hydrazine and weight percent hydrazine, and 10 weight percent of trimethylenetetramine in diphenyl-hydrazine.

When the metal surfaces of the engine which the hydrazine contacts are aluminum or alloys thereof, the compounds found to have particularly good inhibiting ability have the following general formula:

(XIV) OH OH Ilka-(CH2) x-( )H2 wherein x is 0 or 1.

Compositions of this invention utilizing the above compounds include 10 weight percent ethylene glycol in unsymmetrical dimethyl hydrazine and 1 weight percent 1, 3 propylene glycol in hydrazine.

Additional other compounds that may be used in accordance with this invention include hexamethylenetetramine, monohydroxyethyltrihydroxypropyl ethylenediamine, S-aminotriazole and pyrogallic acid and polyoxyethylenes having molecular weights of 300 to 500 such as polyethylene glycol 400.

It should be understood that in the enumeration of particular compositions of the additives of this invention in a hydrazine, as set forth hereinabove, the proportions of the additives are by way of example only and that the proportions may be varied within the broad ranges disclosed with essentially equivalent desirable results.

The amount of the additive compounds in the composition as stated hereinabove is from about 0.1 weight percent to about 15 weight percent based on the total weight of the composition with a preferred range of 0.4 to weight percent of additive. Though less than 0.1 weight percent of the additive compounds may be employed in the composition, it is found that any amount below this figure does not significantly enhance the stability of the hydrazine compound. Above weight percent, the specific impulse of the fuel decreases significantly without an appreciable increase in stability.

The chemical compounds which constitute components of the composition of this invention are known and are commercially available. Processes for their preparation are described in chemical texts such as Organic Chemistry, by Feiser & Feiser, 1944 edition, published by D. C. Heath & Co., New York, as well as other published literature in the chemical field. A lengthy discourse on the various preparations of compounds is therefore not included in this writing.

The rocket propellant compositions of this invention are prepared by mixing the various components together in the amounts required to obtain the desired composition, then subjecting the mixture to agitation such as stirring, shaking, and the like, until a homogeneous composition is obtained. The mixing may be carried out at from to 50 C. and at atmospheric pressure. Generally, 20 C. to 30 C. are preferred. The temperature may be slightly elevated to increase solubility if necessary. It is immaterial in what order the components are added to container in which the mixing is effected. For example, the additive may be added to the hydrazine compound, or conversely, the hydrazine compound may be added to the additive or combination of two or more additives. In addition, the components may be blended in a continuous manner by metering the additive into a flowing stream of the fuel. The following examples are illustrative of the compositions of this invention and their performance.

Example I In order to determine the effects of the decomposition of hydrazine and the eflects of the additives of this invention, several tests were performed in a Setchkin ignition apparatus as described in the Journal of Research of the National Bureau of Standards, 53, 49, 1954. To a Setchkin ignition apparatus was added 95 parts by weight of hydrazine and 5 parts by weight of ethylene diamine tetracetic acid. The apparatus consisted of a spherical flask, 1 liter in capacity, and made of Pyrex glass. It was surrounded by a refractory casing with a half inch air space separating the flask from the casing, which insures uniform heating. Heat was supplied to the upper and lower halves of the casing and the neck of the flask by resistance heaters. The heat input to each of these sections could be varied and adjusted manually, by three variable transformers. Thermocouples were placed in each heating section and two additional ones were in contact with the upper and lower halves of the flask. A thermocouple wire was placed in the lower part of the flask and its temperature recorded on a Leeds & Northrop Speedomax Recorder. In the neck of the flask was a cement-asbestos stopper with three holes. Through these holes passed the thermocouple aforementioned, a glass tube carrying a flushing stream of nitrogen, and an inlet projecting the hydrazine sample through a hypodermic syringe. The tests were performed with probes made by crimping tubes of nickel, aluminum and stainless steel into 24-gauge asbestos-covered thermocouple wires. The metal tubes used for comparing the additives were 0.25 inch in diameter and 2 inches in length, having a wire thickness of 0.025 inch.

First, the flask Was flushed with hydrogen to insure an inert atmosphere. Then the heaters were operated manually to attain 675 F., a temperature at which hydrazine decomposes at a measurable rate. Air was excluded from the Setchkin 1 flask by maintaining a constant nitrogen purge. The quantity of hydrogen injected into the flask each time was 0.02 ml. The amount of hydrazine which displaces 192 ml. of gas at 675 F. was used for the test because it does not create explosive hazards, and yet produces a sufficient temperature rise so that adequate comparison can be made. When a large amount of hydrazine in an additive was examined, a proportionately larger sample was taken so that the quantiy of hydrazine put into the flask each time was 0.2 ml. On adding the hydrazine to the flask the thermocouple temperature rose continuously and reached a maximum in 30-50 seconds. Then it fell off more gradually to the flask temperature. From these asymmetrical-type temperature peaks, the decomposition rate of hydrazine was determined on a comparative basis.

The first criterion of decomposition rate was by the maximum temperature rise, AT, F and the maximum heating rate (dT)/(dt)max., F./sec. If t equals time required to reach the maximum temperature, then AT/t =average heating rate which is about one-half (dT)/(dt)max. since the decomposition is proportional to the AT, the greater the AT, the greater the decomposition. Typical values for hydrazine decomposing on nickel are: T=241 F.; t '=35 seconds; AT/t =6.9 F./sec., (dT) (dt)max.=13 F./sec. The cooling rate initially averaged 1.2 F./sec. in tests. To maintain a consistent cooling rate for all tests, it was necessary to keep a constant flow in the neck purge stream. In this example utilizing 5 weight percent ethylene diamine tetracetic acid, EDTA, a AT of 28 F. was obtained. The percent reduction in AT as compared to no additive being present in the hydrazine was 88 percent. The (dT)/(dt)max. was 0.5 F./ sec. using the additive.

Example II The procedure in Example I was repeated using hydrazine with various other additives. Following Table I illustrates the compositions of this invention and their performance in the Setchkin apparatus desecribed in Example I.

LATIN G A GENTS Weight, Percent (dT/dt)max., Additive Percent A T, F. reduction FJsec.

in A T 1 0 241 12. 4 5 28 88 0. 5 1 112 53 4. 3 5 66 73 6. 8 Hexamethylenetetramine 5 140 42 7. 6 Pyrogallic acid 5 42 83 2.0 Tartaric acid" 1 138 43 5 0 Dipyridyl 5 119 50 4. 3 o-Penanthroline. 1. 6 1O 96 0, 2 Thiourea 5 73 3. 1 l-nitroso-Znaphthol 5 192 20 3. 1 Sulfur 5 156 35 3. 5 Pentane-2, 4-dione 5 148 38 5. 8 Cyanoguanidine 5 12 0. 3 Rubeanic acid 1 138 43 2. 2

1 Percent reduction in AT=100 (1- AT (hydrazine additive) AT (hydrazine alone) The procedure in Example I was repeated utilizing stainless steel probes to determine hydrazine decomposition on such metal and the inhibiting effects of the additives of this invention in decreasing such decomposition. As can be seen, a significant decrease in such decomposition is observed through the addition of small amounts of additives as indicated in the results presented in the following Table II.

TABLE II.HYDRAZINE DECOMPOSITION ON STAINLESS STEEL-EFFECT OF COMPLEXING AGENTS Metal Additive Weight, AT (dT/dt) max.

Stainless Steel 321-... None 103 5. 1

Do EDIA 1 30 0.3

Do Phenanthroline 0. 4 20 0. 2

Example IV The procedure in Example I was repeated wherein aluminum probes were utilized in place of the nickel ones in order to determine hydrazine decomposition on an aluminum surface. The additives of this invention were then combined With the hydrazine and inhibiting effect of such additives were noted from the test run. As results the compositions herein disclosed. The conventional liquid rocket engine as described on page 9 of the book, Rocket Propulsion Elements, by George P. Sutton (1949) published by John Wiley & Sons, New York, consists of storage means for the oxidizer and the fuel, a casing defining a rocket engine chamber having attached to the downstream end thereof an exhaust nozzle and having an injector means adjacent of the upstream casing end. Means are provided to carry the fuel and oxidizer from the storage means to the injector whereby the fuel and oxidizer are intimately mixed and ignited by conventional means such as an electric spark. Thus, the method of operating such an engine comprises storing a liquid oxidizer such as chlorinetrifluor-ide in a storage means and a hydrazine fuel containing five weight percent ethyline diamine tetraacetic acid in the fuel supply means and feeding them to the injector of the engine from where they are injected into the combustion chamber in separate streams to be intimately mixed, igniting the mixture with an electric spark or other means and ejecting from the exhaust nozzle portion of the engine combustion gases to create the desired useful thrust.

Although the invention has been described and illustrated in detail, it is to 'be clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of this invention being limited only by the terms of the appended claims.

We claim:

1. A composition of matter comprising:

a hydrazine and from about 0.1 to 15 percent by weight based on the total composition of a compound having the general formula:

in Table III clearly indicate, the decomposition of the hy- )CHZFGOOH drazine is greatly decreased when additives of this inven- R--N tion are present in the composition. \(GHQXCOOH TABLE III.HYDRAZINE DECOMPOSITION OF ALUMINUM-EFFECT OF AGENTS Metal Additive Weight, AT (dT/ t Percent None 0 81 Aluminum Alloy 5052 1 {Ethleneglycol 5 28 f: g Do 1 {EDTA 1 10 O 2 Propyleneg1yc0l. 5 22 0 8 1 Aluminum alloy containing by weight percent: 0.45 (si-j-F 010 (Cu), 0.10 (Mn), 2.2-2.8 (Mg), 0.15-0.35 (Cr) and 0.10

When the hydrazine fuel compositions of this invention are used in liquid propellant rocket engines, virtually any oxidizer may be used in combination therewith to affect the necessary combustion.

Non-limiting examples of the various oxidizers which may be used: halogens including inter halogens which may be chlorine, bromine, fluorine, chlorinetrifluoride, bromine pentafluoride, bromine monofluonde, chloride monofluoride, iodine pentafluoride, bromine chloride, and iodine chloride; oxides and hydrides of nitrogen which may be nitric oxide, nitrogen dioxide, nitrous oxide, nitrogen trioxide, nitric acid, nitrogen tetroxide, and hydrozoic acid; compounds of a halogen and one or more elements having atomic numbers of 7 and 8 which may be nitrogen trichloride, nitrosyl chloride, chlorine azide, nitrosyl bromide, nitrorgen fluoride, nitrosyl fluoride, nitryl fluoride, nitrogen trifluoride, chlorine monoxide, chlorine pentoxide, chlorine hexoxide, chlorine dioxide, oxygen difluoride, and perchloryl fluoride; strong oxidizing inorganic peroxy acids including chlorosulphonic acid, phosphoric acid, pyrophosphoric acid, fluorosulphonic acid, sulphuric acid, nitric acid, hexafluorophosphoric acid; carboxylic acids may be caproic acid, acetic acid, formic acid, butyric acid, lactic acid, and acrylic acid; oxygen and ozone; hydrogen peroxide; and tetranitramethane.

Example V An additional aspect of the present invention is a method of operating a liquid propellant rocket engine utilizing 3. In a conventional method of operating a liquid fuel rocket engine comprising storing a liquid oxidizer and fuel, feeding said oxidizer and fuel to a rocket engine injector, injecting said fuel and oxidizer into an engine combustion chamber igniting as the fuel therefore the composition of claim 1.

References Cited by the Examiner UNITED STATES PATENTS 3,221,494 12/1965 Chu 6035.4

BENJAMIN R. PADGETT, Primary Examiner.

LEON D. ROSDOL, CARL D. QUARFORTH, REU- BEN BPSTEIN, Examiners.

L. A. SEBASTIAN, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,283,507 November 8, 1966 John Farrar et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 8 line 42 for "T=24l F. read AT=241 F. line 43, for "[dT) (dt)" read (dT)/(dt) TABLE I, first column, line 9 thereof, for "o-Penanthroline" read o-Phenanthroline same TABLE I, in footnote 1, for "AT(hydrazine additive)" read AT(hydrazine additive) column 9, TABLE II, heading to the third column, for "Weight," read Weight, percent Signed and sealed this 9th day of January 1968.

(SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

1. A COMPOSITIONN OF MATTER COMPRISING: A HYDRAZINE AND FROM ABOUT 0.1 TO 15 PERCENT BY WEIGHT BASED ON THE TOTAL COMPOSITION OF A COMPOUND HAVING THE GENERAL FORMULA: HOOC-(CH2)X-N(-R)-(CH2)X-COOH WHEREIN X IS AN INTEGER FROM 1 TO 2 AND R IS SELECTED FROM THE CLASS CONSISTING OF HYDROGEN AND A UNIVALENT ORGANIC RADICAL WHEREINN WHEN R IS A UNIVALENT RADICAL IT HAS FROM 1 TO 9 CARBON ATOMS AND IS SELECTED FROM THE CLASS CONSISTING OF SUBSTITUTED AND UNSUBSTITUTED ALKYL, ARYL, ARALKYL, CYCLOALKYL GROUPS WHEREIN THE SUBSTITUTED GROUPS ARE RADICALS SELECTED FROM THE CLASS CONNSISTING OF PHOSPHONIC ACID, AMINO, IMIDAZOLE, INDYL, PYRROLIDINE, HYDROXY, CARBOXY AND KETO GROUPS.
 3. IN A CONVENTIONAL METHOD OF OPERATING A LIQUID FUEL ROCKET ENGINE COMPRISING STORING A OXIDIZER AND FUEL, FEEDING SAID OXIDIZER AND FUEL TO A ROCKET ENGINE INJECTOR, INJECTING SAID FUEL AND OXIDIZER INTO AN ENGINE COMBUSTION CHAMBER IGNITING AS THE FUEL THEREFORE THE COMPOSITION OF CLAIM
 1. 